The bandgap of III-nitride materials, including (Al, Ga, In)—N and their alloys, extends from the very narrow gap of InN (0.7 eV) to the very wide gap of AN (6.2 eV), making III-nitride materials highly suitable for optoelectronic applications such as light emitting diodes (LEDs), laser diodes, optical modulators, and detectors over a wide spectral range extending from the near infrared to the deep ultraviolet. Visible light LEDs and lasers can be obtained using InGaN in the active layers, while ultraviolet (UV) LEDs and lasers require the larger bandgap of AlGaN.
UV LEDs with emission wavelengths in the range of 230-350 nm are expected to find a wide range of applications, most of which are based on the interaction between UV radiation and biological material. Typical applications include surface sterilization, water purification, medical devices and biochemistry, light sources for ultra-high density optical recording, white lighting, fluorescence analysis, sensing, and zero-emission automobiles.
UV radiation has disinfection properties that inactivate bacteria, viruses, and other microorganisms. A low-pressure mercury lamp may produce UV radiation in the range of 254 nm. Since most microorganisms are affected by radiation around 260 nm, UV radiation is in the appropriate range for germicidal activity. FIG. 1 illustrates a known UV treatment device. A cylindrical chamber 110 houses a UV bulb 112 along a central axis of the chamber 110. The bulb may be encased in a quartz sleeve. UV radiation 114 is emitted from the bulb 112. Untreated water enters the chamber at inlet 116, and flows toward outlet 118, where treated water may be removed from the chamber. A flow control device 120 may prevent the water from passing too quickly past the bulb, assuring appropriate radiation contact time with the flowing water. The chamber is stainless steel.